Incorporating the anterior mitral leaflet to the annulus impairs left ventricular function in an ovine model

Laurencie Brunel¹, Zoe A Williams², Mariko Yata³, Benjamin M Robinson⁴, Innes K Wise⁵, Hugh S Paterson², Paul G Bannon^{4

6}

Affiliations

¹ Faculty of Sciences, School of Veterinary Sciences, The University of Sydney, Sydney, Australia.
² DVC Research Portfolio, The University of Sydney, Sydney, Australia.
³ Department of Cardiology, North Carolina State College of Veterinary Medicine, Raleigh, NC.
⁴ Institute of Academic Surgery, Royal Prince Alfred Hospital, Camperdown, Australia.
⁵ Department of Laboratory Animal Services, The University of Sydney, Sydney, Australia.
⁶ Faculty of Medicine and Health, Central Clinical School-Surgery, The University of Sydney, Sydney, Australia.

PMID: 36003711
PMCID: PMC9390314
DOI: 10.1016/j.xjon.2021.03.010

Incorporating the anterior mitral leaflet to the annulus impairs left ventricular function in an ovine model

Laurencie Brunel et al. JTCVS Open. 2021.

. 2021 Mar 24:7:111-120.

doi: 10.1016/j.xjon.2021.03.010. eCollection 2021 Sep.

Authors

Laurencie Brunel¹, Zoe A Williams², Mariko Yata³, Benjamin M Robinson⁴, Innes K Wise⁵, Hugh S Paterson², Paul G Bannon^{4

6}

Affiliations

¹ Faculty of Sciences, School of Veterinary Sciences, The University of Sydney, Sydney, Australia.
² DVC Research Portfolio, The University of Sydney, Sydney, Australia.
³ Department of Cardiology, North Carolina State College of Veterinary Medicine, Raleigh, NC.
⁴ Institute of Academic Surgery, Royal Prince Alfred Hospital, Camperdown, Australia.
⁵ Department of Laboratory Animal Services, The University of Sydney, Sydney, Australia.
⁶ Faculty of Medicine and Health, Central Clinical School-Surgery, The University of Sydney, Sydney, Australia.

PMID: 36003711
PMCID: PMC9390314
DOI: 10.1016/j.xjon.2021.03.010

Abstract

Objectives: Transcatheter mitral valve prostheses are designed to capture the anterior leaflet and surgical techniques designed to fully preserve the subvalvular apparatus at prosthetic valve insertion both serve to shorten the anterior mitral leaflet height, thus effectively incorporating it into the anterior annulus. This study quantifies the acute effects of incorporating the anterior mitral leaflet into the annulus on left ventricular function.

Methods: Fourteen adult sheep (weight, 48.7 ± 6.2 kg) underwent a mechanical mitral valve insertion on normothermic beating-heart cardiopulmonary bypass, with full retention of the native mitral valve but with placement of exteriorized releasable snares around the anterior mitral leaflet. Continuous measurements of left ventricular mechano-energetics were recorded throughout, alternating incorporating and releasing of the anterior mitral leaflet to the mitral annulus. Echocardiography confirmed the incorporation into the annulus and release.

Results: The independent indices of left ventricular contractility (ie, end systolic pressure volume relationship and preload recruitable stroke work) were both significantly impaired when the anterior mitral leaflet was incorporated to the annulus and restored after release, as were the hemodynamic parameters: cardiac output, stroke volume, stroke work, and left ventricular pressure decreased by 15%, 17%, 23%, and 11%, respectively. Echocardiography demonstrated increased sphericity of the left ventricle during anterior mitral leaflet incorporation.

Conclusions: Incorporating the anterior mitral leaflet to the anterior annulus adversely affected left ventricular contractility, caused distortion of the left ventricle in the form of increased sphericity, and impaired hemodynamic parameters in normal ovine hearts.

Keywords: AML, anterior mitral leaflet; CPB, cardiopulmonary bypass; ESPVR, end systolic pressure volume relationship; LV, left ventricle; VVI, valvular-ventricular interaction; left ventricular function; mitral valve; mitral valve replacement; valvular-ventricular interactions.

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Figures

**Video 1**
The surgeon's view of the mitral valve through the postmortem left atriotomy showing the anterior mitral leaflet (AML) incorporation/release mechanism on an extracted sheep heart after removal of the mechanical valve. The AML is incorporated to the mitral annulus by snaring the 2 polypropylene sutures placed through each trigone. Then the AML is released by releasing the 2 exteriorized snared sutures. Video available at: https://www.jtcvs.org/article/S2666-2736(21)00066-8/fulltext.

**Figure 1**
Schematic representation of anterior mitral leaflet (*AML*) incorporation/release suture placement in the sheep model. The incorporating sutures (*blue*) were passed around the noncommissural chordae to the AML from each papillary muscle and then passed on the ventricular side of the AML and then through the annulus at each trigone to exit the heart through the roof of the left atrium adjacent to the aorta. The releasing suture (*green*) was passed around the 2 incorporating sutures and then exited through the left ventricle wall midway between the bases of the papillary muscles. *PML*, Posterior mitral leaflet; PM, papillary muscle tip.

**Figure 2**
The surgeon's view of the mitral valve through the postmortem left atriotomy showing the anterior mitral leaflet (AML) incorporating/release mechanism on an extracted sheep heart after removal of the mechanical valve. A, The AML is released by releasing the 2 exteriorized snared sutures. B, The AML is incorporated to the mitral annulus by snaring the 2 polypropylene sutures placed through each trigone. *White arrow* indicates postero-medial side of the AML. *Blue arrow* indicates external snares for incorporating the AML (not visible in B).

**Video 2**
Transapical 3-chamber echocardiographic view of the incorporating/release mechanism in the sheep model. The anterior mitral leaflet (AML) (*yellow arrow*) is released then incorporated to the mitral annulus. Ao, Aorta; LV, left ventricle. Video slowed to 35% of normal speed. Video available at: https://www.jtcvs.org/article/S2666-2736(21)00066-8/fulltext.

**Figure 3**
Transapical 3-chamber echocardiographic view of the incorporating/release mechanism in the sheep model. The anterior mitral leaflet (AML) (*yellow arrow*) is released on the left image and incorporated to the mitral annulus on the right image. LV, Left ventricle; Ao, aorta. Scale bar = 1 cm.

**Figure 4**
Schematic representation of anterior mitral leaflet (*AML*) incorporation to the anterior annulus and its adverse effects on left ventricular (LV) contractility, geometry, and hemodynamic parameters in normal ovine hearts. Compared with AML release, incorporating the AML to the mitral annulus was associated with significant decreases in LV contractility and in cardiac output by 15%, stroke volume by 17%, stroke work by 23%, and LV pressure by 11%. *ESPVR*, End systolic pressure volume relationship; *PRSW*, preload recruitable stroke work.

**Figure 5**
Hemodynamic changes following incorporation and release of the anterior mitral leaflet (AML) in all 14 sheep. Compared with AML release, incorporating the AML to the mitral annulus was associated with significant changes in (A) cardiac output, stroke work, stroke volume, and (B) left ventricular (LV) pressures (P < .05). *Box plots* for stroke work, stroke volume, cardiac output and LV pressures are median (interquartile range).

**Figure 6**
Pressure–volume relationship changes following incorporation (n = 31) and release (n = 32) of the anterior mitral leaflet (AML) in 9 sheep. End systolic pressure volume relationship (*ESPVR*) and preload recruitable stroke work (*PRSW*) were significantly impaired during AML incorporation to the mitral annulus versus its release. *Box plots* for ESPVR and PRSW are median (interquartile range).

**Video 3**
Video summary highlighting its importance and clinical relevance. Video available at: https://www.jtcvs.org/article/S2666-2736(21)00066-8/fulltext.

See this image and copyright information in PMC

References

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Incorporating the anterior mitral leaflet to the annulus impairs left ventricular function in an ovine model

Affiliations

Incorporating the anterior mitral leaflet to the annulus impairs left ventricular function in an ovine model

Authors

Affiliations

Abstract

Figures

References

LinkOut - more resources

Full Text Sources